So A Retrospect of Oceanography 



It is by such observations that the main features of oceanic 

 currents have been ascertained and delineated. In sailing 

 ships and steamers of moderate speed valuable indications 

 can be obtained, especially where the currents are strong. 

 As the strongest oceanic currents those in the neighbourhood 

 of the equator occur where the winds are feeblest and calms 

 most frequent, much very valuable information has been 

 received from the observations of sailing ships on long voyages 

 from one hemisphere to the other. It was a frequent experience 

 to be becalmed for days in the regions known as the Doldrums ; 

 but it was the almost invariable experience that, though not 

 moving through the water, the position of the ship on the globe 

 had altered often by as much as 50 or 60 miles in the twenty- 

 four hours. Here the greater part of the change of position 

 was due to current, and the amount of it as logged by an 

 experienced navigator was a trustworthy record of the average 

 current prevailing at the place during the interval of time 

 between two observations. It was not the least of the many 

 services that we owe to Maury, the founder of oceanography, 

 that by collecting and discussing thousands of ships' logs, 

 he produced the first reliable chart of the ocean currents. 

 Modern steamers run so fast that the difference between their 

 position as by observation and by dead reckoning, though 

 important for their commanders, is of little use for our purposes. 



As the "Challenger" was to all intents and purposes a 

 sailing ship, for she was never under steam except when actually 

 sounding and dredging, or occasionally when going into and 

 out of harbour, good results were obtained in this way of the 

 average current every twenty-four hours ; and in the tabulated 

 meteorological observations published in the second volume 

 of the Narrative in the "Challenger" Reports, an entry will 

 be found each day of the current logged. But in the first 

 year of the cruise, a practice was occasionally adopted which, 

 unfortunately, was departed from later, namely, to anchor 

 one of the ship's boats either by the sounding-line or by the 

 dredge-rope, and, from the boat thus stationary, for one of 

 the navigating officers to make careful observations of the 

 current, both at the surface and at certain depths below it 



